FIXING THE GRADE OF DRAINS. 



89 



add one half to the efficiency of a drain, as compared 

 with one which is carelessly made. 



For convenience in reducing the * * Cut ' * column of 

 the notes to feet, inches, and fractions of an inch, which 

 will usually be demanded by workmen in digging a 

 ditch, a table is here appended. In all engineering 

 computations it is desirable to use the decimal scale, 

 but the engineer will soon learn the equivalents of deci- 

 mals of a foot in inches and fractions so that he can 

 write them without referring to the table. Reductions 

 given to the nearest J inch are sufficiently close for 

 practice. 



DECIMALS OP A FOOT REDUCED TO INCHES. 



Ins. 



Foot. 



Ins. 



Foot. 



Ins 



Foot. 



Ins. 



Foot. 



Ins. 



Foot. 



.0104 



i 



.2188 



2| 



.4271 



Si 



.6354 



^t 



.843S 



.0208 



i 



.2292 



f 



4375 



i 



.6458 





.8542 



■ 0313 



i 



. 2396 



i 



.4479 



f 



6563 



i 



.8646 



.0417 



■^ 



. 2500 



3, 



.4'583 



t 



.6667 



8 



.8750 



.OS2I 



|- 



. 2604 



i 



4688 



1- 



.6771 



i 



.8854 



.0625 



f 



.2708 



i 



4792 





.6875 



i 



.8958 



.0729 



i 



.2813 



i 



.4896 



i- 



.6979 



f 



.9063 



. 0833 



1 



.2917 



4- 



.5000 



6 



.70S3 



^ 



-9167 



.0938 



i 



.3021 



f 



.5104 



i 



.7188 



T 



.9271 



.1042 



i 



.3125 



f 



, «i208 



i 



. 7292 



I" 



• 9375 



. 1146 



f 



.3229 



i 



.5313 



f 



.7396 



I" 



• 9479 



.1250 



i 



'3333 



4 



• 5417 



*■ 



.7500 



9 



.95S3 



.1354 



f 



.3438 



i 



■ 5521 





.7604 





.9688 



.14SS 



' f 



• 3542 



i 



.5625 



!• 



.7708 



i 



.9792 



.1563 



1 



.3646 



f 



.5729 



i 



.7813 



T 



.9896 



.1667 



2 



.3750 



■A- 



.583? 



7 



.7917 



i 



1 .00 



.1771 



i 



• 3854 



T 



.5938 



^ 



.8021 



•g- 





.1875 



i 



.39S8 



•| 



.6042 



i 



.8125 



■| 





.1979 



f 



.4063 



1" 



.6146 



f 



.8229 



i 





.2083 



i 



.4167 



s 



6250 



i 



.8333 



10 







11 



X2 



Depth of Drains, 



The depth which drains should be laid is a matter 

 which has received a great deal of attention since the 

 time that underdrainage began to be practised. Ad- 

 vocates of deep and shallow drains have very earnestly 



